Analgesics comprise a large portion of the drugs administered by hospital pharmacies. Analgesics are often prescribed postoperatively to relieve pain. There is great difficulty in properly administering analgesics. The patient need for analgesics varies greatly. Some patients continue to suffer even after given conventional doses of analgesics. Similarly, some patients never request analgesics. Age, hypatic function, renal function, and other medication all affect the pharmacokinetics of analgesics.
Due to the fear of addiction with narcotic drugs, doctors tend to underprescribe the use of analgesics. For the same reason, nurses tend to underadminister analgesics.
In the area of analgesics, there has been much activity in the last several years directed to letting the patient control how much drug he or she receives. It has been found that as a group, patients controlling the quantity of pain killer they receive use less than patients who must request the administration of a pain killer. Apparently, one factor is the psychological relief present when a patient knows he or she is in control of the amount of drug to be received, up to a maximum limit.
The inventors are aware of certain devices that are on the market, or that are in the process of obtaining government regulatory approval, which are directed to the patient-controlled delivery of analgesics. These devices include the Cardiff Palliator by Pye Dynamics Ltd. or Graseby Dynamics of the United Kingdom; the On-Demand Analgesic Computer (ODAC) model JSI 0299 made by Janssen Scientific Instruments; a PCA infuser by Abbott Laboratories, Inc.; the Harvard PCA Pump by C. R. Bard Inc.; and a pump by Deltec Systems Inc. All of these pumps are large and bulky, the smallest pump being the Deltec pump, which is approximately as large as a telephone. All of the above-mentioned devices are electromechanical in nature, requiring a separate power source. Although the Deltec unit may conceivably be worn by patients, it is believed that the remainder of the pumps mentioned above confine the patient to a bed, or some other fixed location.
Another problem associated with these devices is that after the drug is loaded into the pump, certain control factors must be set by the nurse or other person who actually sets up the pump with the patient. These limits may include the minimum time period for delivering a dose of the drug and the size of the drug dose to be delivered when the patient actuates the pump. These limits to be set by the nurse or other personnel provide extra opportunities for error in administering the pain killer and provide additional sources of concern for hospital personnel that must be checked and rechecked during administration of the drug. Yet another problem with existing devices is that they are relatively expensive and may include some rather complex electronic components.
It would be desirable for the medical community to have an apparatus and system for the patient-controlled delivery of a pain killer or other beneficial agent which does not have any of the problems identified above and which can be made at a cost low enough to permit the entire apparatus and system to be disposable, if desired.